1. Field of the Invention
The present invention relates to an image forming apparatus having a plurality of power supply states, a control method, and a memory medium for storing a program.
2. Description of the Related Art
In recent years, in image forming apparatuses, typified by printers, the time required for startup tends to be longer. One of the causes for this is that the amount of data to be expanded in RAM from ROM at startup has been increasing with increase in the number of functions achievable by the image forming apparatuses. To solve this problem, there is a technique where data in RAM remains held therein when the user turns off the power switch, to skip the expansion of the data in the RAM from the ROM when the user turns on the power switch next time, thereby shortening the time required for startup. For example, a “suspend” technique is known where data in RAM is held by continuing energizing the RAM (Japanese Patent Laid-Open No. 09-34578). Also known is a “hibernation” technique where data in RAM is held by temporarily saving the data in the RAM to a hard disk (Japanese Patent Laid-Open No. 2000-82014). In these techniques, while it appears for the user that the apparatus is completely powered off, the time required for startup of the apparatus can be shortened.
In the image forming apparatuses, recently, power control in response to a power switch operation by the user has increasingly come to be executed by software processing. Conventionally, power supply and shutoff were switched from one to the other in step with a power switch operation, like a seesaw switch. However, with the recent requests for reducing the size of the apparatuses and for executing power control methods varying with the switch depression time, image forming apparatuses using a tact switch have been increasing to achieve the requests. An image forming apparatus provided with a tact switch is powered on upon depression of the switch when the apparatus is in its power-off state, and powered off upon depression of the switch when the apparatus is in its power-on state. In such a configuration, power control can be performed by software in accordance with the switch depression time.
If the switch is depressed for a period of time not intended by the user due to a wrong operation, etc., however, power control not intended by the user will be performed. To avoid such a problem, a technique is known where, when a switch depression for a period of time exceeding a given time is detected, such a depression is determined to be a wrong operation (Japanese Patent Laid-Open No. 2008-293430).
Normally, in the power-off state where the image forming apparatus is not energized, a program, etc. cannot be previously expanded in the RAM because no power is distributed to the RAM. In this case, after the image forming apparatus is put in the power-on state to restart energization of the interior of the apparatus, and then processing such as expansion of a program in the RAM is performed, the apparatus can become usable to the user. By contrast, by continuing power distribution to the RAM even after the power-off operation (high-speed startup standby state), it is possible to skip processing such as expansion of a program in the RAM at the time of power-on from the power-off state, shortening the time required until the apparatus becomes usable to the user. The convenience to the user can be improved by performing the shift to the power-off state or the high-speed startup standby state according to the depression time of the power switch.
It is necessary that the high-speed startup standby state, which is a RAM energized state, appears the same as the power-off state for the user, and thus the appearance of the image forming apparatus, such as display of LEDs, is configured to be the same as that in the power-off state. However, since the display of LEDs, etc. will be the same even if the user wrongly operates the power switch depression time, such a situation may occur that the user may recognize the apparatus as being in the power-off state but actually the apparatus is in the high-speed startup standby state. In particular, it is not preferable, from the standpoints of safety and power consumption, to leave the apparatus in its high-speed startup standby state that is an internally energized state unintentionally.
According to Japanese Patent Laid-Open No. 2008-293430, when the power switch is kept depressed over a period of time exceeding a given time, this is detected as a wrong operation. However, such detection of a wrong operation is not effective for a case where the apparatus is wrongly shifted to the high-speed startup standby state, although it should be shifted to the power-off state, because the depression time is short.